18 A STUDY OF NATURAL ^lETHODS OF 



unless broken apart, they are attached end to end, like a string of sausages^ 

 for these fruiting bodies are formed from the branching tubes of the 

 mycelium (the vegetative part of the mould). Wherever the mycelium 

 comes to the surface of the dead grub, it branches profusely, and each of 

 the tips then becomes constricted into a line of numerous spores. Hence, 

 the numbers produced by a single grub are unthinkable — a tiny speck o 

 this oreen powder taken on the point of a pin and placed under the 

 microscope is a revelation, for the mass of spores is beyond counting. 

 Therefore, it is easy to understand how the soil becomes thoroughly 

 inoculated Avith this contagion as it is ploughed and cultivated. Further- 

 more, probably a single spore is sufficient to bring aljout the disease, 

 when ingested with the soil ])y the grub, if the climatic conditions are 

 right. 



Therefore, in spite of our apparent lack of success in multiplying" 

 the Muscardine fungus artificially, in the cabinet, it would at least appear 

 worth while to attempt to assist nature in the distribution of these friendly 

 allies, especially at the time that dead grubs are so abundant in the field. 

 While the epidemic was on, it was an easy matter to gather up any quantity 

 of the spore-laden soil ; and we distributed this to several other infested 

 localities where the diseases were not known to occur. 



Recent observations (January, 1921) at Greenhills demonstrate that' 

 the fungus is already becoming virulent again. Many of the newly- 

 hatched grubs have succumbed to it ; and in spite of the rather high 

 temperature, we have found it attacking and destroying the third-stage 

 grubs of Lepidiota frenchi. Then, too, the young grubs that we have 

 brought to the insectary, in soil from these infected fields, have died off 

 in great numbers — in some instances the whole lot succumbing after a 

 few days. The extreme virulence is not so hard to understand, for the 

 insectary is shaded and open, hence considerably cooler than the field ; 

 then, too, the pots have a more constant supply of water — the ideal 

 conditions for the act'vities both of the fungus and other diseases. 



Suggestions for making use of these Friendly Allies. 



Though there is no hope of producing an annual epidemic, even in 

 the most favoured local ties, I nevertheless regard these parasitic organisms, 

 as our most valuable allies in the control of white grubs. I feel certain 

 that they are accountable for the sudden total disappearance of these 

 pests in certain districts ; and they undoubtedly are a most important 

 factor in holding grubs, as well as other insects, in check. It is a fact well 

 recoo^niscd that if almost any insect pest were permitted to multiply 

 absolutely without restriction, there would soon be no room for man or 

 other living creatures upon the earth. Since these diseases have such 

 possibilities of assisting us, it certainly behoves everyone witli grub- 

 infested land to have his soil inoculated as soon as possible, if, perchance, 

 nature has not already done it for him. 



